Field of Disclosure
Embodiments described herein generally related to systems and methods for reducing complexity and processing time in relay selection and power allocation schemes for cognitive multiple-input multiple-output buffer-aided decode-and-forward relay networks.
Description of the Related Art
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Currently, wireless communications is witnessing substantive and continuous developments to fulfil the growing demands of network users for high-speed multimedia services with high quality of service. In this regard, power and frequency parameters are amongst the most important resource considerations in wireless communication networks and are subjected to strict laws to control their allocation and usage among service providers.
Using underlay cognitive radio (CR) networks, the secondary user (SU) and the primary user (PU) can access the same spectrum simultaneously as long as the secondary network (SN) interference on the primary network (PN) does not exceed a certain interference threshold. However, interference will affects both the PN and SN due to the simultaneous usage of the same spectrum. This issue requires more investigation in designing joint power scheduling schemes.
A major drawback in the current state of the technology is how to handle the power rate and data rate of the PN during the selection of a most suitable relay device between a source device and a destination device and a way to optimize antenna transmission power of the PN. Another challenge occurs in selecting the most suitable relay device, or optimal relay device, in multiple-input multiple-output (MIMO) cooperative networks because it requires optimizing the antenna transmission power for each possible relay device, followed by calculating a single-hop rate and then selecting the relay device with the maximum normalized rate which is considered to be a slow and complicated process.
Unlike conventional unbuffered relaying schemes, data transmission in buffer-aided relaying is not restricted to two consecutive time slots to accomplish end-to-end packet transmission. Instead, information packets could be stored in a relay buffer of certain maximum size for an arbitrary number of time slots until the best channel conditions on the relay-destination link are met. This buffering operation splits the power allocation problem into two problems, the first being on the source-relay link (link between source device and relay device) and the other is on the relay-destination link (link between relay device and destination device). As a result, complexity of targeted optimized functions may be decreased.
One practical relay selection scheme for buffer-aided relaying is Max-Link relay selection protocol. In this protocol, at any given time slot, based on the channel state information measured, a decision is made whether the source or the relay conducts its transmission. For implementation in MIMO systems, Max-Link relay selection may be less effective for MIMO cooperative networks than for single-antenna implementation because a set of channel gains affect the link capacity and no general measure of MIMO channel quality is defined. Accordingly, an iterative process in which MIMO-based relay selection algorithms are set based on discrete iterative stochastic optimization for the uplink of cooperative MIMO networks may be needed. Furthermore, there is a need to develop a solution to enhance the efficiency of power and frequency usage, including hybrid combination use of CR, cooperative communication, power allocation, buffer-aided relaying and MIMO antenna schemes that maximizes the single-hop normalized sum rate of a PN and SN rates.